Show signs of non-atomic form of radiation (6)
I believe the answer is:
betray
'show' is the definition.
(thesaurus)
'signs of non-atomic form of radiation' is the wordplay.
'signs of non atomic form of' becomes 'bet' (I can't explain this - if you can you should give a lot more credence to this answer).
'radiation' becomes 'ray' (ray is a kind of radiation).
'bet'+'ray'='BETRAY'
Can you help me to learn more?
(Other definitions for betray that I've seen before include "Hand someone over to an enemy" , "26 [SELL]" , "Cheat on" , "Reveal (intentionally or unintentionally)" , "Breach the trust of" .)